1. Field of the Invention
The present invention relates to a structure of IC cards.
2. Description of the Prior Art
Conventionally, for so-called IC cards, there has been commonly and widely adopted a structure in which internal components such as an electric circuit board with specified electronic components or the like incorporated therein are arranged within a frame, the upper and lower sides of which arrangement are covered by a pair of metal panels.
It is noted that the term "IC card" herein refers to those which are formed into card-like or flat-plate shape and which are provided with electronic circuits or electric circuits including semiconductor circuits. For example, the IC card is construed as including cards which are called by various other different designations, from PC cards, modem cards, LAN cards or memory cards to electronic cards, and which have similar basic constructions.
As the structure of such IC cards, there has been known one in which the frame serving as the outer frame of the card is divided into upper and lower two divisions, and the upper and lower frames are integrated with upper and lower metal panels, respectively, in which arrangement the upper and lower frames are coupled with each other by ultrasonic welding process, by which the IC card is assembled.
More specifically, as an example is shown in FIGS. 16 to 19, an IC card 101 according to the prior art comprises a frame 102 made of resin and constituting the outer frame of the card main body, an electric circuit board 103 into which specified electronic components or the like 104 have been incorporated, a connector 105 to be attached on one end side of the electric circuit board 103, and a pair of metal panels 107, 108 which cover the upper and lower sides (front and rear) of the card 101 including the electric circuit board 103 and the connector 105. In addition, the connector 105 is designed to obtain electrical connection with equipment in which the IC card 101 is to be used (e.g., personal computers or the like).
The frame 102 made of resin is divided into upper and lower two divisions, thus comprising an upper frame 102U and a lower frame 102L. The upper frame 102U and the upper panel 107 are integrated together to form an upper exterior member 110U, while the lower frame 102L and the lower panel 108 are integrated together to form a lower exterior member 110L. These frames 102U, 102L and metal panels 107, 108 are integrated, respectively, in the molding process of the resin frames 102U, 102L, for example, by the so-called panel-frame integrally molding technique.
Then, after the electric circuit board 103 and the connector 105 connected thereto are interposed between the upper exterior member 110U and the lower exterior member 110L the members 110L, 110U are coupled together, by which the IC card 101 is assembled. In addition, the upper exterior member 110U is illustrated upside down for a better understanding of its structure in FIG. 19, whereas the upper exterior member 110U will be reversed 180.degree. from the illustrated state of FIG. 19, as indicated by one-dot chain line in FIG. 19, and combined with the lower exterior member 110L in the actual assembling process.
In the coupling surface of either one of the upper and lower frames 102U, 102L (the lower frame 102L in this prior-art example), as apparent from FIG. 17, a welding protrusion 111 (welding margin) the cross section of which has been set to specified size and shape is formed so as to, for example, continue along the perimeter of the frame 102L.
Then, the upper and lower exterior members 110U, 110L are combined together so that the welding protrusion 111 and the end face of the upper frame 102U come into contact with each other. In this state, while the contact portion is held pressurized from above and below, ultrasonic vibrations are given to fuse the welding protrusion 111, by which the upper and lower frames 102U, 102L are coupled with each other at their end faces.
With such an arrangement adopted, not only the time-consuming and laborious bonding process can be eliminated, but also a stronger fixation can be attained, compared with the case where metal panels are bonded to the upper and lower sides of an integral-unit frame. Moreover, the fixation width of the frame can be set narrower, so that a large mounting area for electronic components or the like within the IC card can be ensured.
In addition, in the coupling surfaces of the upper and lower frames 102U, 102L, slits 112U, 112L which reach the metal panels 107, 108 are formed, respectively, so as to correspond to each other. Prior to the assembly of the upper and lower exterior members 110U, 110L, for example, annular metallic rings (not shown) are preliminarily fitted to these slits 112U, 112L, by which conduction between the upper and lower metal panels 107, 108 can be obtained in the assembled state. As a result, the electronic components or the like 104 placed on the electric circuit board 103 can be electrically protected from static electricity and the like applied from outside, more effectively.
As a structure designed for improvement in the durability to static electricity by making the upper and lower metal panels conducting with each other as stated above, although other than the type that the frame is divided upper and lower, there is known such a structure as disclosed in Japanese Utility Model Laid-Open Publication No. HEI 4-63284, in which the upper and lower metal panels are subject to a bending process at their side edge portions to form claw portions which are engageable with each other, while the resin frame has vertical through gaps formed at sites corresponding to the claw portions, in which arrangement when the card is assembled. The claw portions of the upper and lower metal panels are engaged with each other within the gaps so that the conduction between the two metal panels can be obtained.
However, in the prior-art IC card 101, since the upper exterior member 110U and the lower exterior member 110L are coupled together by ultrasonic welding, applying ultrasonic vibrations to coupling portions in the welding process would cause the vibration energy to reach the electronic components or the like 104 on the electric circuit board 103, thus giving rise to a possibility that these electronic components or the like 104 may be damaged. To avoid this problem, it is necessary to ensure more than a certain spacing between the upper and lower metal panels 107, 108 and the electronic components or the like 104. This would lead to problems in design, for example that the height of the electronic components or the like 104 is limited responsively.
Also, in the prior-art IC card 101, for obtaining the conduction between the upper and lower metal panels 107, 108 with a view to enhancing the durability to static electricity derived from outside, it would be necessary to provide special parts (e.g., the aforementioned annular metallic rings), and besides to provide, on the upper and lower frames 102U, 102L, the slits 112U, 112L for fitting the special parts. As a result, the number of component parts involved is increased, the molding dies for the frames 102U, 102L become complex, and moreover the number of man-hours for assembly is also increased, as further problems.